JPS61167537A - Manufacture of information recording disc - Google Patents

Abstract

PURPOSE:To obtain an information recording disc whose electrically conductive surface layers of both the surfaces are connected with each other, by forming a large diameter hole on a three-layer structural member to be obtained by laminating electrically conductive surface layers on both he surfaces of the electrically non-conductive layer and hot press processing is performed after a small diameter pin has been passed through the hole. CONSTITUTION:a) A three-layer structural member A is manufactured by lami nating surface layers 1a, 1b whose viscosity applicable at the temperature for molding afterward is lower than that of a central layer 2 and, moreover, having electrical conductivity, on both the surfaces of the electrically nonconductive central layer 2. b). A hole 3 whose diameter is larger than that of a center hole of an information recording disc to be obtained after completion is formed on the center of the three layer structural member A. c). The laminated member A is loaded to a molding machine while a pin 5 of the molding machine, whose diameter is smaller than the hole 3 is passed through the hole 3 and hot press molding is applied to the laminated member A. In this instance, both of the surface layers are made to connect with each other by making a part of the both side surface layers 1a, 1b flow between the pin 5 and hole 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing an information recording disc, such as a video disc or a digital audio disc, and in particular to a method for manufacturing an information recording disc, such as a video disc or a digital audio disc, and in particular, a method for manufacturing an information recording disc, such as a video disc or a digital audio disc, and in particular, a method for manufacturing an information recording disc, such as a video disc or a digital audio disc, and in particular, a method for manufacturing an information recording disc, such as a video disc or a digital audio disc. This invention relates to a method for manufacturing a capacitive information recording disc in which an information signal is reproduced by changing the capacitance between the electrode of a reproduction needle that relatively scans the surface in accordance with a change in geometric shape. It is something.

[Prior art and its problems]

For example, capacitive high-density information signal recording discs such as video discs are made by mixing a large amount of carbon black powder and other stabilizers with vinyl chloride resin to make a conductive resin composition. It is manufactured by conveying the material to a mold and heating and compressing it.

Therefore, the video disc manufactured in this way is
Since a large amount of carbon blank powder is contained in an unnecessary part, that is, the center of the video disc in the thickness direction, more expensive carbon blank powder is required than necessary, which inevitably leads to high costs. Become something.

Therefore, a type of video disc that does not contain carbon black powder in the center has been proposed. That is, for example, a type of plate with a three-layer structure, in which a non-conductive first plate is provided with conductive second plates on both sides, and information signals are recorded by compression molding means has been proposed (Patent Application No. 58). -24
No. 6611).

If it is a three-layer structure type like this one, the amount of expensive carbon black powder used can be reduced, which has a great cost advantage, but if it is a three-layer structure type, it is completely fine. I've come to realize that it's nothing.

In other words, if a video disc is simply formed by compression molding a three-layer structure plate, the surface layers on both sides of the video disc will not be connected to each other, and this will cause problems between the video disc and the playback device. It has been found that the grounding is insufficient in some cases, and as a result, static electricity builds up, deteriorating the reproduced image quality (dropouts, reduction in S/N, inability to reproduce recorded information, etc.).

In addition, there may be a drawback that a spark phenomenon may occur, which may damage the electrode of the regenerating needle.

[Means for solving problems]

a step of forming a three-layer structure consisting of a surface layer having conductivity necessary for reproducing recorded information and a non-conductive center layer having a viscosity higher than that of the surface layer at molding temperature, and the three-layer structure; A step of forming a hole in the body with a diameter larger than the center hole for configuring the center hole of the information recording disc, and forming a three-layer structure so that a pin of a molding machine is inserted into the hole of the three-layer structure in which the hole is formed. The body is placed in a molding machine, and by molding, a part of the surface layer material of the three-layer structure flows to the hole wall surface, connecting the surface layer materials on both sides of the center layer. Manufacture.

〔Example〕

FIGS. 1a to 1e are process explanatory diagrams of one embodiment of the information recording disc manufacturing method according to the present invention.

First, as shown in Figure 1a, a three-layer structure consisting of a surface layer with conductivity necessary for reproducing recorded information and a non-conductive center layer with a viscosity higher than that of the surface layer at the molding temperature. Make plate A. Note that this three-layer structure plate A can be produced using conventionally proposed composite plate manufacturing means, so the details thereof will be omitted here.

Incidentally, la and lb are surface layers having conductivity necessary for reproducing recorded information, and these surface layers 1a and Ib have a thickness of, for example, about 0.05 mm, and are coated with a lubricant such as silicone oil and a heat stabilizer. It is composed of a conductive thermoplastic resin such as a vinyl chloride resin containing additives such as plasticizers and lubricants, and conductive substances such as carbon black powder in the amount necessary for the capacitance regeneration method, and 2 is surface layer 1
This central layer 2 is a central layer between a and 1b, and has a thickness of about 1.15 mm, for example, and is made of vinyl chloride containing lubricants such as Noricon oil, additives such as heat stabilizers, plasticizers, and lubricants. It is made of a substantially non-conductive thermoplastic resin such as a thermoplastic resin.

It is important to select the center layer 2 so that its viscosity is higher than that of the surface layers 1a and 1b at the temperature during molding into a video disc, which will be described later.

Next, as shown in the figure, a hole 3 for forming the center hole of the video disc is formed in the center of the plate A by, for example, punching means.

It is important that the diameter of this hole 3 is slightly larger than the standard value for the center hole of a video disc, for example, about one order of magnitude larger.

Next, as shown in Figure C, the plate A with the holes 3 drilled therein is placed at a predetermined position in the compression molding machine B, and molding is performed.

In the figure, 4 is an air cylinder of compression molding machine B, 5 is a center pin, 6 is a stamper, 7 is a mold, and 8 is a stamper stopper, and the diameter of the center pin 5 is the center of the video disc standard. It is the same as the diameter of the hole.

This compression molding process is carried out in the same manner as the previous compression molding process, but the center pin 5 is inserted into the hole 3 of the plate A at the same time as or prior to the compression molding process, so that the compression molding As shown in d and e of the same figure, when
The material of the surface layers 1a and lb of the plate body A is poured into the gap between the wall surface of the hole 3 and the center pin 5, and the material is poured into the gap between the wall surface of the hole 3 and the center pin 5.
As shown in FIG. 2, the conductive resin that is the material of the surface layers 1a and 1b are connected through the holes 3, and the surface layers 1a and 1b are electrically connected.

Through the compression molding process, the materials of the surface layers 1a and 1b are connected through the holes 3, and the surface layers 1a and 1b are electrically connected (forming the center hole of the disk), and information signals are transmitted to the surface layers 1a and 1b. lb is recorded, the center pin 5 is lowered by the air cylinder 4, the molded disk C is taken out by the disk ejecting means, and then a part of the overflow is cut off by an outer periphery trimming process to produce, for example, a video disk.

Video discs produced through the process described above are
The main advantage is that the center layer is not conductive and only the surface layer is conductive, which means that it is constructed without using more carbon black powder than necessary, making it cheaper in terms of material costs. have.

Moreover, not only is the amount of carbon black powder reduced, but also the above process creates an electrically short circuit between the surface layers on both sides of the center layer, which leads to problems with the regeneration equipment. Since it is sufficiently grounded, it is possible to prevent static electricity from accumulating, thereby preventing deterioration of the reproduction characteristics and further damage to the electrode of the reproduction needle. That is, the material for the center layer 2 is selected to have a higher viscosity at the molding temperature than the material for the surface layers 1a and 1b of the plate A, and the material for the center layer 2 is selected in advance in the compression molding process to form the center hole of the video disc. Since a perforated hole 3 is formed and compression molding is performed with a pin inserted into the hole 3, the surface layers 1a and 1b can be electrically connected.

The above also constitutes the center hole of the video disc at the same time.

When the center hole is constructed in this way, it is more accurate than when the center hole is constructed through a center hole machining process using a conventional punching method, and there are no problems with eccentricity or hole diameter.・〈You can obtain something with less scratchiness.

〔effect〕

The amount of conductive material used can be reduced, and information recording discs can be produced at a correspondingly lower cost.

Furthermore, both surfaces of the information recording disk are electrically conductive, and therefore static electricity can be prevented from forming, resulting in a disk with little deterioration in reproduction characteristics.

Moreover, a center hole with high precision can be obtained.

Furthermore, manufacturing is simple; for example, the formation of the center hole and the conduction of the surface layer can be done in one process. In other words, the formation of the center hole also means the conduction of the surface layer, so there are not many manufacturing steps. , the manufacturing cost is not high either.

[Brief explanation of drawings]

FIGS. 1a to 1e are explanatory diagrams of one embodiment of the method for manufacturing an information recording disc according to the present invention. A... Three-layer structure plate, B... Compression molding machine, C...
- Disk, Ia, Ib...Surface layer, 2... Center layer, 3... Hole, 5-... Center pin. Patent applicant: Victor Japan Co., Ltd. 4 + person Katsumi Udaka? 1 figure

Claims (1)

[Claims] a step of forming a three-layer structure consisting of a surface layer having conductivity necessary for reproducing recorded information and a non-conductive center layer having a viscosity higher than that of the surface layer at molding temperature, and the three-layer structure; A step of forming a hole in the body with a diameter larger than the center hole for configuring the center hole of the information recording disc, and forming a three-layer structure so that a pin of a molding machine is inserted into the hole of the three-layer structure in which the hole is formed. The three-layer structure includes a step of placing the body in a molding machine and molding the three-layer structure so that part of the surface layer material flows to the hole wall surface so that the surface layer materials on both sides of the center layer are connected. A method for manufacturing an information recording disc.